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Old 22-07-2020, 09:44   #1
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Critical DC components not available in 12v / 24v

Is anyone aware of any critical DC components on a boat that would only be readily available in 12v and not 12v / 24v?


I know historically there were very good reasons for using 12v but I'm trying to figure out if that is still the case. It seems that every single component I've looked at is dual 12v/24v and, if that's the case, wouldn't it only make sense to have everything 24v?


I'm not referring to engine start batteries but the deep cycle house batteries.
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Old 22-07-2020, 09:49   #2
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Re: Critical DC components not available in 12v / 24v

24v will limit your selection/availability in some things and will likely cause higher $ in some too won't it? I can't tell you which.
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Old 22-07-2020, 09:52   #3
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Re: Critical DC components not available in 12v / 24v

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Originally Posted by NaClyDog View Post
Is anyone aware of any critical DC components on a boat that would only be readily available in 12v and not 12v / 24v?


I know historically there were very good reasons for using 12v but I'm trying to figure out if that is still the case. It seems that every single component I've looked at is dual 12v/24v and, if that's the case, wouldn't it only make sense to have everything 24v?


I'm not referring to engine start batteries but the deep cycle house batteries.
Even if you were to go with a 24v house bank, there are converters to step down to 12v if you ever found something that just outright required it.
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Old 22-07-2020, 10:03   #4
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Re: Critical DC components not available in 12v / 24v

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24v will limit your selection/availability in some things and will likely cause higher $ in some too won't it? I can't tell you which.
Will it though? I haven't been able to locate a single component that wasn't 12v/24v out of the box so to speak.


From winches, electronics, fridges/freezers and pumps.


I would think from the wiring alone on a 40-50 foot vessel it would be worth it.


That said, when something seems so obvious to me it likely means I'm completely missing something hence the question.
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Old 22-07-2020, 10:44   #5
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Re: Critical DC components not available in 12v / 24v

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Will it though? I haven't been able to locate a single component that wasn't 12v/24v out of the box so to speak.
24v is no problem for the house system. There is little that will not run on both 24v and 12v out of the box, or in the worse case at least little equipment that is not readily available in a 24v version.

Conversely, if you have a larger boat then a lot of high powered equipment such as anchor winches and autopilot drives are not available in 12v. When this high power equiment is available in a 12v version this option tends to be less efficient than the 24v equivalent.

The only domestic exceptions that require 12v on our boat are the NMEA 2000 power supply and the VHF (24v VHF radios are available, but these tend to be commercial units).

24v to 12v converters are not expensive, if you do require 12v. They often run at a constant 13.8v, which helps reliability and reduces voltage drop problems, but there is very little equipmet that will require the conversion
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Old 22-07-2020, 10:58   #6
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Re: Critical DC components not available in 12v / 24v

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The only domestic exceptions that require 12v on our boat are the NMEA 2000 power supply and the VHF (24v VHF radios are available, but these tend to be commercial units).



Thank you. Everything I had looked into seemed to support both voltages but you are quite right about these two. Just checked the specs on my B&G vhf and sure enough, 12V.
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Old 22-07-2020, 11:11   #7
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Re: Critical DC components not available in 12v / 24v

24V moves you out of the auto/RV (12V) market and into the industrial automation/controls (24V) market. IME there is far more choice for most things that we use on boats, and a much better range of quality. As Noelex points out, “marine” instruments and radios are the holdouts in terms of reasonable availability. Lighting, motors, and most other equipment can be had in 24V.

The big difference is knowing where and how to shop. For the stuff that you don’t get at the marine store you’re now looking at an electrical wholesale house. Having an account and a relationship can go a long way to getting good pricing (frequently beating the internet). And knowing the quality levels and features of various lines and types of equipment can take a while, but pays dividends in long life and low maintenance.
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Old 22-07-2020, 11:31   #8
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Re: Critical DC components not available in 12v / 24v

Curious what triggered this question?

I ask, as I have been interested in creating a 24v battery bank for better efficiency, and reduced costs. Sounds like with all key items being 12/24v capable, this is a valid option.
Put a step down for a few 12v things i need (LED lights etc).
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Old 22-07-2020, 11:52   #9
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Re: Critical DC components not available in 12v / 24v

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Curious what triggered this question?

I ask, as I have been interested in creating a 24v battery bank for better efficiency, and reduced costs. Sounds like with all key items being 12/24v capable, this is a valid option.
Put a step down for a few 12v things i need (LED lights etc).
In preparation for getting our boat, I've been taking "mini" boat courses put on by our local yacht club. Basic diesel engines, basic boat plumbing, basic DC power, etc... It seems to just be enough knowledge to try and prevent you from doing anything too stupid while away from the dock.



Everything pointed to 24v being better but it just seemed to not be that common and I wanted to try to see if there was a reason I was missing.
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Old 22-07-2020, 12:02   #10
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Re: Critical DC components not available in 12v / 24v

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Originally Posted by NaClyDog View Post
In preparation for getting our boat, I've been taking "mini" boat courses put on by our local yacht club. Basic diesel engines, basic boat plumbing, basic DC power, etc... It seems to just be enough knowledge to try and prevent you from doing anything too stupid while away from the dock.



Everything pointed to 24v being better but it just seemed to not be that common and I wanted to try to see if there was a reason I was missing.
It is basically a matter of history. Sailors are slow to change things, but things do change. 12v has been an automotive standard for a long time and this mixed into the yacht industry.

If I was going to start a new electrical system from scratch, I'd go 24v. There are many RVs that have already gone that route.
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Old 22-07-2020, 12:22   #11
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Re: Critical DC components not available in 12v / 24v

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Originally Posted by NaClyDog View Post
In preparation for getting our boat, I've been taking "mini" boat courses put on by our local yacht club. Basic diesel engines, basic boat plumbing, basic DC power, etc... It seems to just be enough knowledge to try and prevent you from doing anything too stupid while away from the dock.



Everything pointed to 24v being better but it just seemed to not be that common and I wanted to try to see if there was a reason I was missing.


24 v is better

Availability ? Traditionally it was a bit more difficult

It was always only available in that shop across town

These days with the internet everything is possible.

You can get more work out of a 24 v piece of equipment

More work translates into higher price for certain equipment
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Old 22-07-2020, 19:47   #12
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Re: Critical DC components not available in 12v / 24v

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Is anyone aware of any critical DC components on a boat that would only be readily available in 12v and not 12v / 24v?
The main problem is the extent of conversion an existing boat requires. There are a number of fairly expensive items where the voltage must be selected at the time of purchase and where conversion or replacement is costly:
- Most motorized items, windlass, bow thruster, bilge pumps, freshwater pumps, washdown pumps, macerator pumps and electric heads, power winches, autopilot drive motors
- Fans
- Inverters and chargers
- solar charge controllers (a few auto detect or are convertible but not most)

As stated upthread, the main areas where 24v products are simply not available are:
- NMEA2000 powered items as 12v is baked into the standard
- VHF radios except for very expensive commercial products
- HF radios except for very expensive commercial products
- Repurposed RV/automotive items such as chargers for some laptops and phones, vacuum cleaners, chargers for power tool batteries, portable CPAPs

For most sailboat engines a full conversion from 12v to 24v isn't feasible with engine controls and the starter motor being the problem areas. Larger diesels do have 24v starter motors readily available but not the 4 cylinder and smaller Yanmars.

Vanner equalizers aren't mentioned on CF much but are a common way to support large, intermittent 12v loads with a system that is 24v overall. They make for a complex system that is beyond the troubleshooting ability of most people though
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Old 22-07-2020, 22:59   #13
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Re: Critical DC components not available in 12v / 24v

nmea 2000 is only 12v.

lots of vhf radios only 12v.


most things are available as one or the other. very few things are both. not sure where you are seeing all these dual voltage things. a 12/24 windlass? no way.
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Old 23-07-2020, 00:42   #14
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Re: Critical DC components not available in 12v / 24v

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most things are available as one or the other. very few things are both. not sure where you are seeing all these dual voltage things.
Some examples of equipment that I have purchased for my boat that will run on 12 or 24v includes:

Chartplotters, AIS, Radar, Autopilot computer, USB plugs (therefore charging of phones, tablets, cameras etc) fridge, solar controllers, fans, fuses, circuit breakers, busbars, wiring, battery monitor, the batteries themseves, internal lights, navigation lights.

For my above units the same model will accept 12v or 24v. Just plug it into either voltage and it will work, although of course we run this equipment on 24v.

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a 12/24 windlass? no way.
The anchor windlass needs to be ordered in either a specific 12v or a 24v model. Most medium sized windlasses are readily available in either voltage, but if you have a choice the higher voltage model will run better and be easier to wire.

Larger windlasses are only available in 24v versions as the current draw becomes impractical on 12v.
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Old 23-07-2020, 01:20   #15
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Re: Critical DC components not available in 12v / 24v

On my boat I had a 24V house bank which powered everything except the Raymarine nav-instruments, VHF, and Furuno weather fax and navtex. They were all on 12V, so I used a Mastervolt 24-12 V DC converter and a separate 12V battery.
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